CHRNA3 and chronic obstructive pulmonary disease: Genome-wide association studies found SNPs in the alpha-neuronal nicotinic acetylcholine receptor subunit (CHRNA3/5, Chr 15q25) locus responsible for increased susceptibility [155,156], while genetic variants in Hedgehog-interacting protein (HHIP, Chr 4q31) and family with sequence similarity 13 member A (FAM13A gene, Chr 4q22) loci were shown to have a protective effect against COPD and lung cancer among smokers [157,158].